Outcomes for patients with multi-morbidity (MM) are often poor, in part because of low adherence to self-management behaviors (SMB).Research has identified key determinants of SMB for individual diseases and shown the powerful influence that illness representations and medication beliefs have on these behaviors. Yet, little is known about the impact of illness representations in the context of MM where beliefs about one illness and its treatments may be at odds, or symbiotic, with those for comorbidities. Without this knowledge, our ability to provide optimal self-management support for MM patients is limited. The goal of this study is to determine how beliefs about chronic illness and their treatments affect SMB in the context of MM and to translate this information into self-management support counseling modules for use in future interventions. We will focus on patients with chronic obstructive pulmonary disease (COPD), a disabling and costly health problem, and evaluate the impact of 3 comorbid conditions that differ in level of self-management complexity and symptomatology: hypertension (HTN), diabetes (DM),and depression. The study design is rooted in the Self Regulation Model (SRM), a theory of health behaviors that has been used to develop interventions, but has only been applied to research on behaviors around single diseases. Depression is of great interest in the study of the SRM because patients with depression often have maladaptive representations and perceptions of illness. By understanding the interplay of illness representations and medication beliefs and their impact on SMB in the context of comorbidities, we will advance both the SRM and the clinical care of patients with MM. The Specific Aims are to: 1) Examine the interactive effects of COPD, HTN, and DM related cognitive and emotional illness representations and medication beliefs on patients' self-management of these conditions over time? 2) Assess the association of major depression with COPD SMB over time and evaluate the pathways, via illness representations and medication beliefs, mediating this relationship?(3) Guided by findings from Aims 12 and the SRM, develop and pilot test education and counseling modules for COPD patients with MM to promote adherence to SMB. We will conduct a mixed methods prospective cohort study of 400 COPD patients with HTN or DM in NY City and Chicago and interview them every 3 months for 15 months. We will also conduct interviews during and after COPD exacerbations to assess changes illness representations and their impact on SMB. For Aim 3, we will conduct qualitative interviews with patients who have good or low medication adherence to understand cognitive processes that guide SMB and to identify the self-management strategies they use. We will then create counseling modules to improve self-management and pilot them among 100 patients. The study will expand the SRM to MM, elucidate how patients respond to varying beliefs in the context of MM, and provide prototype self-management support counseling modules for application to a future, fully developed intervention to improve SMB and outcomes for adults with MM.